The present invention relates broadly to surface acoustic wave (SAW) devices, and in particular to a X33 cut quartz substrate for temperature compensated surface acoustic wave (SAW) devices.
Surface acoustic waves which contain both compressional and shear components in phase quadrature, propagating nondispersively along and bound to solid surfaces, were discovered in the 1880s. As an example, earthquakes furnish sources for propagating these waves on the Earth's surface. It is of importance for electronic applications that if the solid is a piezoelectric material, the surface acoustic energy is complemented by a small amount of electric energy. This electric energy provides the physical mechanism for the coupling between conventional electromagnetic signals and propagating surface acoustic wave (SAW). The coupling is attained by means of interdigitial transducers (IDT). Surface acoustic wave devices have led to a versatile microminiature technology for analog signal processing in the frequency range 10.sup.7-10.sup.9 Hz. Notable devices include bandpass filters, resonators, oscillators, pulse compression filters, and fast Fourier transform processors. Application areas include the color television consumer market, radar, sonar, communication systems, and nondestructive testing.
The present invention provides an X-cut quartz crystal wherein the orientation of the surface of the quartz crystal is normal to the X crystalline axis as defined by the IRE "Standards on Piezoelectric Crystals, 1949" (Published in the Proceedings of the IRE, pp 1378-1395, December 1949).